The big LIGHTS thread 2011-2014

Discuss the eternal "Which fork/bike/tyres should I buy?" questions.
-Archie-
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Re: The big LIGHTS thread 2011-2012

Postby -Archie- » Wed Apr 03, 2013 10:05 am

JamesB wrote:When batteries from China described as rubbish is that a short battery lifespan, inability to recharge or what?

Low capacity, i.e. quite short run time.

And if they`re that bad where are better 4 x 18650 packs available from ? I can only find non China sources of single 18650s all others seem to be packs from China.

Have a look at eBay, for example...

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Re: The big LIGHTS thread 2011-2012

Postby -Archie- » Wed Apr 03, 2013 10:08 am

Neal_ wrote:If you want really good cells then make sure they're from Japan (Sanyo, Panasonic, Samsung etc)

The latter is Korean manufacturer. :)

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Re: The big LIGHTS thread 2011-2012

Postby Neal_ » Wed Apr 03, 2013 10:16 am

-Archie- wrote:
Neal_ wrote:If you want really good cells then make sure they're from Japan (Sanyo, Panasonic, Samsung etc)

The latter is Korean manufacturer. :)


I did wonder if they were definitely all Japanese but couldn't be bothered checking ;)

bamba
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Re: The big LIGHTS thread 2011-2012

Postby bamba » Thu Apr 04, 2013 09:14 am

Regarding 18650 batteries, far better to find your self an old laptop battery an get some good cells, imo far better than any second rate stuff from the far east, and often for free. Check your works it dept. Diy has a guide on here for "harvesting" them.

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Re: The big LIGHTS thread 2011-2012

Postby -Archie- » Thu Apr 04, 2013 09:42 am

bamba wrote:Regarding 18650 batteries, far better to find your self an old laptop battery an get some good cells, imo far better than any second rate stuff from the far east, and often for free.

Thats' true, but measurement of cells' "state of health" requires some additional equipment, while most users have just ordinary charger and perhaps DMM...

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Re: The big LIGHTS thread 2011-2012

Postby bamba » Thu Apr 04, 2013 11:15 am

Not really, just check there voltage, charge them and check there taking charge and hold charge, then test them in a torch.
If you get a good run time from them then consider them good.measure the current draw if you want and google the battery code to find its milli amp hour rating to see if its on par.

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Re: The big LIGHTS thread 2011-2012

Postby bamba » Thu Apr 04, 2013 11:16 am

Not really, just check there voltage, charge them and check there taking charge and hold charge, then test them in a torch.
If you get a good run time from them then consider them good.measure the current draw if you want and google the battery code to find its milli amp hour rating to see if its on par.

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diy
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Re: The big LIGHTS thread 2011-2012

Postby diy » Thu Apr 04, 2013 11:34 am

I agree with Bamba, a sophisticated charger or DC amp meter is not necessary really. Charge and use and check the start and end voltage to work out how good a cell is. Noting that it takes a few cycles to get a cell that has spent its life at 3.75v to take 4.2v.

Also very few laptops don't have w/h or mAh on the pack.

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Re: The big LIGHTS thread 2011-2012

Postby -Archie- » Thu Apr 04, 2013 11:49 am

For single-cell torches, method "Try and see" is appropriate, too (although I dislike idea of using cell without protective circuit , for safety reasons). Measurement of actual cell's parameters is necessary for assembling the high-capacity batteries, though.

As for the voltages - 3,7 V is nominal voltage, and 4,2 V is voltage at full charge (for majority of types). There's no need to cycle the cell to reach 4,2 V level: if cell and charger are not broken, it will do that on very first charge, regardless of previous cell usage.

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diy
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Re: The big LIGHTS thread 2011-2012

Postby diy » Thu Apr 04, 2013 12:31 pm

But if all the cells have come out of the same laptop pack and hold the same voltage, there really isn't much point in doing anything more to determine the capacity.

You typically find the voltage is way off, if the cell is damaged in some way.

I personally also find that mah goes up after about the 2nd or 3rd charge. Its possible that this is because the cell packs have spent the last 6-12 months in a cupboard though rather than a specific feature of upping the voltage. Either way I would not expect a recycled laptop pack to be optimal after the first use.

i.e. want to avoid people binning perfectly good cells.

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Re: The big LIGHTS thread 2011-2012

Postby -Archie- » Thu Apr 04, 2013 13:09 pm

diy wrote:But if all the cells have come out of the same laptop pack and hold the same voltage, there really isn't much point in doing anything more to determine the capacity.

Capacity and voltage are totally different things: there's no way to determine capacity by checking voltage only...

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KokaKona
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Re: The big LIGHTS thread 2011-2012

Postby KokaKona » Thu Apr 04, 2013 14:22 pm

-Archie- wrote:
bamba wrote:Regarding 18650 batteries, far better to find your self an old laptop battery an get some good cells, imo far better than any second rate stuff from the far east, and often for free.

Thats' true, but measurement of cells' "state of health" requires some additional equipment, while most users have just ordinary charger and perhaps DMM...


I use all the slightly unscientific ways mentioned of trying to guess the health of my harvested cells, but I was wondering what equipment you'd recommend Archie to do the job properly? Is it expensive, because if so I guess it goes against the grain of getting the cells for free in the first place? I wondered for example whether there was some cheap PC software/hardware which could charge-discharge and record data...

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diy
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Re: The big LIGHTS thread 2011-2012

Postby diy » Thu Apr 04, 2013 15:39 pm

-Archie- wrote:
diy wrote:But if all the cells have come out of the same laptop pack and hold the same voltage, there really isn't much point in doing anything more to determine the capacity.

Capacity and voltage are totally different things: there's no way to determine capacity by checking voltage only...


I think you already know, that I know that ;)

However, it is fairly easy to work out rough capacity given a known current requirements and starting and ending voltage.

See: http://lygte-info.dk/info/BatteryCharge ... %20UK.html

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Re: The big LIGHTS thread 2011-2012

Postby -Archie- » Fri Apr 05, 2013 01:12 am

diy wrote:I think you already know, that I know that ;)

I was pretty sure, but your last statement sounded like if you're suggesting to determine capacity based just on voltage, sorry. :oops:

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Re: The big LIGHTS thread 2011-2012

Postby -Archie- » Fri Apr 05, 2013 01:55 am

KokaKona wrote:I use all the slightly unscientific ways mentioned of trying to guess the health of my harvested cells, but I was wondering what equipment you'd recommend Archie to do the job properly? Is it expensive, because if so I guess it goes against the grain of getting the cells for free in the first place? I wondered for example whether there was some cheap PC software/hardware which could charge-discharge and record data...

Well, sometimes it's wise to invest initially, to save later. :)

The cell's state is determined by such major parameters as capacity, internal resistance, and self-discharge rate. Most important is, obviously, first one. It's very convenient to measure it by using processor-based universal charger, widely available as "hobby charger": I personally use Turnigy AccuCell 6. It is equipped with RS232-TTL data port (serial output), providing connection to PC via appropriate adapter: typically to USB. I've connected Bluetooth transmitter to it, so it transfers measurement data wirelessly. To collect & analyze the data, I use freeware LogView software, powerful and highly configurable, exporting results to the Excel spreadsheet and pictures with charge/discharge curves. It requires also separate power supply (charger itself capable to provide 6A current, but for playing with 18650, less expensive 2A supply is enough), adapter(s) for battery connection, and optionally thermal sensor.

Image Image

Please note that sometimes such chargers are not calibrated properly at the factory, so it's worth checking/adjusting by external voltage reference.

Image

For resistance measurement, I use Sinometer SM8124 impedance meter, but it requires a bit of modding. Device itself is very good, with proper four-wire Kelvin scheme, but is supplied with ordinary DMM-style test leads where cables are internally shorted together, spoiling whole purpose of using it. You'll have to buy correct Kelvin probes, or make ones yourself. I prefer the latter method, and used spring-loaded gold micro test pins and holders to make them.

Image Image

As for self-discharge, I use Victor 86B meter with optical RS232 interface and USB receiver: supplied "DMM Data Processor" software collects the data, and is also capable of exporting directly into Excel spreadsheet.

Image Image

On the photo below, you can see one of my self-made high capacity 12-cell 6P2S battery assembled with 18650 cells extracted from discarded notebook batteries and matched by parameters, using mentioned apparatus.

Image


This particular set of equipment, of course, is just my personal setup: you can choose any other pieces more appropriate for your requirements. For beginning, hobby charger alone is probably sufficient. Good luck!

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KokaKona
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Re: The big LIGHTS thread 2011-2012

Postby KokaKona » Sun Apr 07, 2013 22:16 pm

-Archie- wrote:
KokaKona wrote:I use all the slightly unscientific ways mentioned of trying to guess the health of my harvested cells, but I was wondering what equipment you'd recommend Archie to do the job properly? Is it expensive, because if so I guess it goes against the grain of getting the cells for free in the first place? I wondered for example whether there was some cheap PC software/hardware which could charge-discharge and record data...

Well, sometimes it's wise to invest initially, to save later. :)
...
This particular set of equipment, of course, is just my personal setup: you can choose any other pieces more appropriate for your requirements. For beginning, hobby charger alone is probably sufficient. Good luck!


Comprehensive response, thanks Archie! :shock: I'm wondering about that hobby charger now...

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Ouija
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Re: The big LIGHTS thread 2011-2012

Postby Ouija » Wed Apr 17, 2013 19:23 pm

Some interesting battery packs just popped up on ebay.

Black Yellow
Gold Yellow
Turquoise Yellow

Makes you wonder if you can take the 18650's out and replace them and then stuff them back in the aluminium container or if the batteries are just normal shrink wrapped affairs stuffed in an aluminium can?

Also... 6 cell pack for only £14.

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Re: The big LIGHTS thread 2011-2012

Postby JamesB » Thu Apr 18, 2013 06:02 am

Do look interesting and if I was in market for better battery pack would pursue; but to add to my previous praise of SingFire SF-90 (chinese) I continue to be impressed by it. http://dx.com/p/singfire-sf-90-cree-xm- ... 650-172351 but in blue---no idea if lumens quoted is correct !

Used in earnest on road last weekend and 2.5 hours on HIGH no sign light dimming and fabulous beam, OK for 30 mph down narrow country lane. Very impressed with it as a road light (beam may be too focussed for MTB) @ £22 or less can`t go wrong :D :D

Only criticism was screw mount thread poor so ended up with self tap screw and araldite...

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diy
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Re: The big LIGHTS thread 2011-2012

Postby diy » Thu Apr 18, 2013 07:01 am

Also available from a uk(ish) seller for a couple of quid more.
http://www.7dayshop.com/7dayshop-super- ... head-light

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Re: The big LIGHTS thread 2011-2012

Postby JamesB » Thu Apr 18, 2013 07:50 am

---and probably a lot quicker than seven weeks delivery too :(

BUT having got 2 SF 90 I am happy with them


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